01 -
Combine shallots, garlic, thyme, and cremini mushrooms in a food processor. Process until finely minced. Transfer mixture to a bowl.
02 -
Pat the beef tenderloin dry with paper towels. Brush evenly with Dijon mustard, then season on all sides with 2 teaspoons salt and black pepper. Heat vegetable oil in a large pan over medium-high heat, then sear beef until evenly browned on all sides, about 6–8 minutes. Remove from heat and place in the refrigerator to chill.
03 -
In the same pan, melt unsalted butter over medium heat. Add mushroom mixture and cook, stirring frequently, until moisture evaporates and mushrooms are deep golden and dry, approximately 8–10 minutes. Season with 1/4 teaspoon salt. Spread onto a plate and refrigerate until completely cooled.
04 -
On a large piece of plastic wrap dusted lightly with flour, arrange the prosciutto slices slightly overlapping to form a rectangle. Spread the cooled mushroom mixture evenly over prosciutto. Place the chilled beef tenderloin on top. Using the plastic wrap as a guide, roll the prosciutto and mushrooms tightly around the beef. Wrap firmly and refrigerate for at least 30 minutes.
05 -
Heat oven to 180°C. Line a baking sheet with parchment paper. On a lightly floured surface, roll out the puff pastry to a rectangle large enough to fully encase the beef. Unwrap the beef roll and place it in the centre of the pastry. Brush the pastry edges with beaten egg. Fold the pastry over the beef, sealing the edges and trimming excess dough. Place seam-side down on the prepared baking sheet.
06 -
Brush the entire pastry surface with egg wash and sprinkle with flaky salt if desired. Score the pastry for decoration. Bake on the centre rack until the pastry is golden brown and an internal temperature of 60–65°C is reached in the centre of the beef (approximately 45–50 minutes).
07 -
Remove from the oven and let rest for 20 minutes to maintain juiciness. Transfer to a cutting board, slice cleanly with a sharp knife, and serve immediately.